A hard disk drive (HDD) comprising a magnetic disk has conventionally been used. The recent trend is to further increase the capacity of a hard disk. In order to increase the recording density for increasing the capacity, there has been disclosed a technique in which the track density is decreased by reducing track widths.
There has also been disclosed another technique for increasing the track density. In this technique, the track widths are decreased to an extent that data is written to adjacent tracks in a partly overlapping manner. Such a recording technique is often referred to as shingle recording. However, when this technique is applied, the data stored in the adjacent track in a partly overlapping manner is lost. Therefore, data writing must be performed per unit track group composed of a plurality of tracks (for example, see Japanese Patent Application Publication (KOKAI) No. 2006-338731).
However, employing the technique disclosed in Japanese Patent Application Publication (KOKAI) No. 2006-338731 takes long time to write data because the writing must be performed per unit track group.